1. Field of the Invention
The present invention relates to a linear motion guiding apparatus in which a passage forming member formed of resin is built into a body of movable member.
2. Description of the Related Art
The applicant has already proposed a technical idea that, in a movable block of a linear motion guiding apparatus, a pair of ball passage forming portions extending along the opposite longitudinal sides of a loaded-ball running groove, a ball returning passage forming portion and a pair of direction changing passage-inner guide forming portions were integrally formed of resin with a body of the movable block (refer to Japanese Patent Provisional Publication No. H7-317,762).
More specifically, when a resin forming is carried out, the body of the movable block is inserted in a die, and the ball passage forming portions, the direction changing passage-inner guide forming portions or the ball returning passage forming portion is integrally formed with the block body.
In the conventional movable block obtained by the integral forming, the block body is inserted in the die, as mentioned above. When the block body has a large size, a large-scaled die is required to be used. It is not easy to prepare such a large-scaled die, and there is actual restriction in size. The ball passage forming portions located at the opposite longitudinal sides of the ball running groove extending along the longitudinal direction of the block body are thin and long, with the result that molten resin may not reach every part of the space for forming the ball passage forming portions during the resin forming treatment.
Increase in number of gates formed on the die may solve the above-mentioned problem of misrun of the molten resin. However, when the block body is inserted in the die, the block body may deteriorate the run of the molten resin.
When the movable block has a pair of wing portions, which face right and left-hand side portions of the guide rail so that the guide rail is held between the wing portions, and there are four trains of balls between the right and left-hand side portions of the guide rail and the right and left-hand wing portions of the moving block, and more specifically, the upper and lower trains of balls are arranged at each of a gap between the right-hand side portion of the guide rail and the corresponding right-hand wing portion of the moving block and another gap between the left-hand side portion of the guide rail and the corresponding left-hand wing portion of the moving block, the block body inserted in the die may deteriorate the run of the molten resin in the width direction of the moving block.
An object of the present invention is therefore to provide a linear motion guiding apparatus in which a resin-formed body for forming a rolling member circulation passage is formed separately from a body of a movable member so as to permit easy formation of the resin-formed body, and such a resin-formed body is able to be built in the body of the movable member, ensuring integral formability of the maximum number of unit parts for defining the rolling member circulation passage.
In order to attain the aforementioned object, a linear motion guiding apparatus comprises:
a guide member provided with a rolling member running track, and
a movable member arranged so as to be movable along the guide member through a large number of rolling members, said movable member being provided with (i) a rolling member running counter-track corresponding to the rolling member running track of said guide member, (ii) a rolling member returning passage arranged away from said rolling member running counter-track by a prescribed distance and in parallel therewith and (iii) a pair of direction changing passages for connecting the rolling member running counter-track and the rolling member returning passage to permit circulation of the rolling members,
characterized in that:
a resin-formed body for forming a rolling member circulation passage comprises a pair of rolling member passage forming portions extending along both longitudinal sides of said rolling member running counter-track, a returning passage forming portion for forming the rolling member returning passage and a pair of direction changing passage-inner guide forming portions for forming inner peripheral guide portions of said direction changing passages, said resin-formed body being separately formed from a body of said movable member; and
at least two portions of (a) said pair of rolling member passage forming portions, (b) said returning passage forming portion, (c) one of said pair of direction changing passage-inner guide forming portions and (d) another of said pair of direction changing passage-inner guide forming portions are connected with each other through integral forming so that said resin-formed body can be built in the body of said movable member.
Embodiments of the combination of these portions (a) to (d) for the resin-formed body for forming the rolling member circulation passage may include the following three examples:
the first example in which the resin-formed body comprises (i) an integral body of the pair of rolling member passage forming portions and the pair of direction changing passage-inner guide forming portions, and (ii) the returning passage forming portion separately formed from the integral body
the second example in which the resin-formed body comprises (i) an integral body of the pair of rolling member passage forming portions, the returning passage forming portion and one of the pair of direction changing passage-inner guide forming portions, and (ii) another of the pair of direction changing passage-inner guide forming portions separately formed from the integral body; and
the third example in which the resin-formed body is manufactured by preparing an integral body of the pair of rolling member passage forming portions, the returning passage forming portion and the pair of direction changing passage-inner guide forming portions, and then dividing the pair of rolling member passage forming portions and the returning passage forming portion in longitudinal intermediate portions thereof into respective two parts.
According to the present invention, the resin-formed body for forming the rolling member circulation passage is separately formed from the body of the movable member. Even if the movable member has a large size, the flow of molten resin is not therefore restricted by the body of the movable member unlike the conventional prior art in which the body of the movable member and the resin-formed body are integrally formed with each other, and it is possible to ensure proper run of molten resin through increase in a number of gates in the die, thus leading to an excellent formability. In general, it is hard to achieve proper run of molten resin especially at the rolling member passage forming portions extending along the longitudinal sides of the rolling member running counter-track, and it is therefore effective to separately form the resin-formed body from the body of the movable member in the same manner as the present invention.
The rolling member circulation passage is formed by the resin-formed body. Therefore, the direct positioning can be achieved in the relative positional relationship between the direction changing passage-inner guide forming portions and the rolling member passage forming portion, as well as the relative positional relationship between the direction changing passage-inner guide forming portions and the returning passage forming portion, and the continuity of the rolling member circulation passage is properly ensured, thus leading to smooth run of the rolling members.
Since the rolling member passage forming portions are located along the both longitudinal sides of the rolling member running counter-track, the direction changing passage-inner guide forming portions having a proper relative positional relationship with the rolling member passage forming portions are accurately set on the both ends of the rolling member running counter-track.
Maintenance of a proper relative positional relationship of the direction changing passage-inner guide forming portions with the rolling member returning passage causes the direction changing passage-inner guide forming portions to be accurately connected to the inner surface of the rolling member returning passage.
Especially, change in a running direction of the rolling members takes place in the connection area of the rolling member passage forming portions with the direction changing passage-inner guide forming portions as well as in the connection area of the direction changing passage-inner guide forming portions with returning passage forming portion. When two portions in such a connection area are connected with each other by integral forming, a step for assembling these two portions is not required, thus making it possible to ensure a smooth continuity of these two portions without being affected by accuracy of assembly.
The rolling member returning passage may be a through-hole formed in the body of the movable member, the resin formed-body may comprise the pair of direction changing passage-inner guide forming portions and the rolling member passage forming portions extending along the both longitudinal sides of the rolling member running counter-track, and the rolling member passage forming portions and at least one of the pair of direction changing passage-inner guide forming portions may be connected with each other through integral forming.
When the rolling member passage forming portions and the direction changing passage-inner guide forming portions are integrally formed with each other so as to provide the smooth connection area in this manner, it is possible to achieve the smooth run of the rolling members in the connection area of these portions, thus improving circulation property of the rolling member without providing any returning passage forming portion made of resin. Such a construction causes easy manufacture of the apparatus due to no existence of the returning passage forming portion.
The present invention may have additional features that a rolling member retainer is provided, the rolling member retainer being able to retain the rolling members in a train with a prescribed distance kept between adjacent two of the rolling members, and the rolling member retainer having side edge portions projecting from both sides of each of the rolling members; and guide grooves for guiding the side edge portions of the rolling member retainer are formed on an entire periphery of the rolling member circulation passage.
The present invention may have additional features that a retaining portion is provided on the rolling member passage forming portion, for preventing the rolling member retainer being out of place, when the movable member is removed from the guide member, and a guide portion is continuously formed on the entire periphery of the rolling member circulation passage, for guiding the side edge portions of the rolling member retainer.
Such provision of the rolling member retainer permits the smooth run of the rolling members by means of the rolling member retainer, due to proper maintenance of continuity of the guide portion for the rolling member retainer.
Since the guide portion for the rolling member retainer having a small thickness is not formed by inserting the body of the movable member in a die and then injecting molten resin into the die, but is separately formed from the body of the movable member, position of gates can freely be determined without being restricted by the body of the movable member, with the result that molten resin can reach, during formation of the guide portion, the entire space therefor, which is formed in the die.
The present invention may have additional features that each of the direction changing passage-inner guide forming portions has a thin sheet portion, which is to be brought into contact with the end face of the body of the movable member, and each of the direction changing passage-inner guide forming portions is connected to the rolling member passage forming portions or the returning passage forming portion by means of the thin sheet portion.
When each of the direction changing passage-inner guide forming portions is connected to the rolling member passage forming portions by means of the thin sheet portion, deformation of the thin sheet portion can absorb distortion, which occurs between the direction changing passage-inner guide forming portion and the rolling member passage forming portion, or between the direction changing passage-inner guide forming portion and the returning passage forming portion. Accordingly, it is possible to maintain an accurate positional relationship between the end of the direction changing passage-inner guide forming portion and the rolling member passage forming portion or between the direction changing passage-inner guide forming portion and the returning passage forming portion.
The thin sheet portion is urged against the flat end face of the body of the movable member by a clamping force, which is applied to the side cover plate. The position of the direction changing passage-inner guide forming portion can therefore be corrected through deformation of the thin sheet portion, even when the direction changing passage-inner guide forming portion is not correctly positioned relative to the end face of the body of the movable member. In addition, the thin sheet portion can firmly be secured between the side cover plate and the body of the movable member by the clamping force, which is applied to the side cover plate, thus preventing the direction changing passage-inner guide forming portion from being incorrectly placed.
The apparatus of the present invention may have the construction that the guide member comprises a guide rail; the movable member comprises a movable block, which is provided with a horizontal portion, which faces an upper surface of the guide rail and a pair of wing portions, between which the guide rail is held at right and left-hand side surfaces thereof, two trains of the rolling members are arranged in a gap between the upper surface of the guide rail and a lower surface of the movable block, and a single train of the rolling members is arranged in each of gaps between the right and left-hand side surfaces of the guide rail and:both of the wing portions, so as to provide a total number of trains of four.
The apparatus of the present invention may have the construction that the guide member comprises a guide rail; the movable member comprises a movable block, which is provided with a pair of wing portions, between which the guide rail is held at right and left-hand side surfaces thereof, and two trains of the rolling members are arranged in each of gaps between the right and left-hand side surfaces of the guide rail and both of the wing portions, so as to provide a total number of trains of four.
In these cases, the respective four direction changing passage-inner guide forming portions may be formed into an integral body, or the respective two direction changing passage-inner guide forming portions at each of the right and left-hand sides of the movable block may be formed into an integral body.
The apparatus of the present invention may have the construction that the guide member comprises a guide rail; the movable member is provided with a horizontal portion, which faces an upper surface of the guide rail and a single wing portion, which faces one side surface of the guide rail; a single train of the rolling members is arranged in a gap between the one side surface of the guide rail and the single wing portion, and another single train of the rolling members is arranged in a gap between the upper surface of the guide rail and a lower surface of the horizontal portion in a vicinity of a corner of the guide rail.
The apparatus of the present invention may have the construction that the guide member comprises a guide rail; the movable member comprises a movable block, which is provided with a pair of wing portions, between which the guide rail is held at right and left-hand side surfaces thereof, and a single train of the rolling members is arranged in each of gaps between the right and left-hand side surfaces of the guide rail and both of the wing portions, so as to provide a total number of trains of two.
The apparatus of the present invention may have the construction that the guide member comprises a guide rail; the movable member comprises a movable block arranged along one side surface of the guide rail; and two trains of the rolling members are arranged in a gap between the one side surface of the guide rail and the movable block.
The apparatus of the present invention may have the construction that the guide member comprises a spline shaft; and the movable member comprises an outer tube, which is movably supported on the spline shaft through a plurality of trains of the rolling members.
In addition, according to the present invention, there is also provided a linear motion guiding apparatus comprising:
a guide rail provided with two rolling member running tracks on each of right and left-hand side surfaces of the guide rail, so as to provide a total number of the rolling member running tracks of four; and
a movable block provided with a pair of wing portions, between which the guide rail is held at the right and left-hand side surfaces thereof, each of said wing portions having on an inner surface thereof two rolling member running counter-tracks corresponding to said two rolling member running tracks of the guide rail, so as to provide a total number of the rolling member running counter-tracks of four, said movable block having four endless circulation passages, which are formed by four rolling member returning passages arranged in parallel with said four rolling member running counter-tracks, respectively, and rolling member returning passages for connecting both ends of each of said four rolling member running counter-tracks with both ends of each of said four:rolling member returning passages, respectively
characterized in that:
a resin-formed body comprises, for each of said endless circulation passages, a pair of rolling member passage forming portions extending along both longitudinal sides of said rolling member running counter-track, a returning passage forming portion for forming the rolling member returning passage and a pair of direction changing passage-inner guide forming portions for forming inner peripheral guide portions of said direction changing passages, said resin-formed body being separately formed from a body of said movable block;
said resin-formed body is divided into two body-parts, which are arranged on the wing portions of the movable block, respectively, so as to form the two endless circulation passages at an inner side of each of the wing portions; and
in each of the two body-parts, the rolling member running counter-track and the pair of direction changing passage-inner guide forming portions are formed into an integral body, and the returning passage forming portion is separately formed from said integral body.
According to the present invention, the resin-formed body for forming the rolling member circulation passage is separately formed from the body of the movable block. Even if the movable block has a large size, the flow of molten resin is not therefore restricted by the body of the movable block unlike the conventional prior art in which the body of the movable block and the resin-formed body are integrally formed with each other, and it is possible to ensure proper run of molten resin through increase in a number of gates in the die, thus leading to an excellent formability. In general, it is hard to achieve proper run of molten resin especially at the rolling member passage forming portions extending along the longitudinal sides of the rolling member running counter-track, and it is therefore effective to separately form the resin-formed body from the body of the movable block in the same manner as the present invention.
Especially, since the resin-formed body is divided into the two body-parts, each of which forms two endless circulation passages, a proper run of molten resin can be ensured, even when the block of the movable block has a larger width.
The rolling member circulation passage is formed by the resin-formed body. Therefore, the direct positioning can be achieved in the relative positional relationship between the direction changing passage-inner guide forming portions and the rolling member passage forming portion, as well as the relative positional relationship between the direction changing passage-inner guide forming portions and the returning passage forming portion, and the continuity of the rolling member circulation passage is properly ensured, thus leading to smooth run of the rolling members.
Since the rolling member passage forming portions are located along the both longitudinal sides of the rolling member running counter-track, the direction changing passage-inner guide forming portions having a proper relative positional relationship with the rolling member passage forming portions are accurately set on the both ends of the rolling member running counter-track.
Maintenance of a proper relative positional relationship of the direction changing passage-inner guide forming portions with the rolling member returning passage causes the direction changing passage-inner guide forming portions to be accurately connected to the inner surface of the rolling member returning passage.
Especially, change in a running direction of the rolling members takes place in the connection area of the rolling member passage forming portions with the direction changing passage-inner guide forming portions. When these two portions in such a connection area are connected with each other by integral forming, a step for assembling these two portions is not required, thus making it possible to ensure a smooth continuity of these two portions without being affected by accuracy of assembly.
The present invention may have additional features that a rolling member retainer is provided, the rolling member retainer being able to retain the rolling members in a train with a prescribed distance kept between adjacent two of the rolling members, and the rolling member retainer having side edge portions projecting from both sides of each of the rolling members; and guide grooves for guiding the side edge portions of the rolling member retainer are formed on an entire periphery of the rolling member circulation passage.
Such provision of the rolling member retainer permits the smooth run of the rolling members by means of the rolling member retainer, due to proper maintenance of continuity of the guide portion for the rolling member retainer.
Since the guide portion for the rolling member retainer having a small thickness is not formed by inserting the body of the movable block in a die and then injecting molten resin into the die, but is separately formed from the body of the movable block, position of gates can freely be determined without being restricted by the body of the movable block, with the result that molten resin can reach, during formation of the guide portion, the entire space therefor, which is formed in the die.
The present invention may have additional features that each of the direction changing passage-inner guide forming portions has a thin sheet portion, which is to be brought into contact with the end face of the body of the movable block, and each of the direction changing passage-inner guide forming portions is connected to the rolling member passage forming portions or the returning passage forming portion by means of the thin sheet portion.
When each of the direction changing passage-inner guide forming portions is connected to the rolling member passage forming portions by means of the thin sheet portion, deformation of the thin sheet portion can absorb distortion, which occurs between the direction changing passage-inner guide forming portion and the rolling member passage forming portion, or between the direction changing passage-inner guide forming portion and the returning passage forming portion. Accordingly, it is possible to maintain an accurate positional relationship between the end of the direction changing passage-inner guide forming portion and the rolling member passage forming portion or between the direction changing passage-inner guide forming portion and the returning passage forming portion.
The thin sheet portion is urged against the flat end face of the body of the movable member by a clamping force, which is applied to the side cover plate. The position of the direction changing passage-inner guide forming portion can therefore be corrected through deformation of the thin sheet portion, even when the direction changing passage-inner guide forming portion is not correctly positioned relative to the end face of the body of the movable block. In addition, the thin sheet portion can firmly be secured between the side cover plate and the body of the movable block by the clamping force, which is applied to the side cover plate, thus preventing the direction changing passage-inner guide forming portion from being incorrectly placed.